JP4498727B2 - Alumina sintered body and manufacturing method thereof - Google Patents

Alumina sintered body and manufacturing method thereof Download PDF

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JP4498727B2
JP4498727B2 JP2003398206A JP2003398206A JP4498727B2 JP 4498727 B2 JP4498727 B2 JP 4498727B2 JP 2003398206 A JP2003398206 A JP 2003398206A JP 2003398206 A JP2003398206 A JP 2003398206A JP 4498727 B2 JP4498727 B2 JP 4498727B2
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alumina
sintered body
alumina sintered
pore
alumina particles
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JP2005154227A (en
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淳司 左近
俊彦 鈴木
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NGK Insulators Ltd
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Description

本発明は、連通気孔を有する気体透過性の（以下、「多孔質の」ということがある）アルミナ焼結体及びその製造方法に関し、さらに詳しくは、気体透過性の各種工業用材料、例えば、ガスセンサの測定電極用の電極保護層や集塵機におけるフィルタ等として好適に用いられる、気孔径及び気孔率等の連通気孔の特性が所望の範囲に精密に制御された多孔質のアルミナ焼結体及びその効率的な製造方法に関する。 The present invention relates to a gas-permeable (hereinafter sometimes referred to as “porous”) alumina sintered body having continuous air holes and a method for producing the same, and more specifically, various gas-permeable industrial materials, for example, Porous alumina sintered body whose characteristics of continuous air holes such as pore diameter and porosity are precisely controlled within a desired range, suitably used as an electrode protective layer for a measurement electrode of a gas sensor or a filter in a dust collector, and the like The present invention relates to an efficient manufacturing method.

ガスセンサの測定電極用の電極保護層や集塵機におけるフィルタ等の気体透過性の各種工業用材料として、多孔質のアルミナ焼結体が好適に用いられている。ガスセンサとしては、例えば、自動車排気ガス中の酸素濃度を測定し、エンジン内での燃焼状態を検出するために用いられる酸素センサがある（特許文献１）。 Porous alumina sintered bodies are suitably used as various gas-permeable industrial materials such as an electrode protective layer for a measurement electrode of a gas sensor and a filter in a dust collector. As a gas sensor, for example, there is an oxygen sensor used for measuring the oxygen concentration in automobile exhaust gas and detecting the combustion state in the engine (Patent Document 1).

近年、自動車の性能向上のために、エンジンの高性能化のみならず、エンジンオイルやガソリン中に、リン、亜鉛、マグネシウムあるいはカルシウムといった様々な添加剤が添加されている。しかし、これらの添加剤が排気ガス中に混入すると、酸素センサ表面に付着して拡散抵抗層の連通孔を塞いだり、あるいは測定室内の測定電極に付着して電極を劣化させ、センサの出力が低下したり、応答性が低下するといった問題点が生じていた。また、このような多孔質のアルミナ焼結体は、例えば、適度な粘性をもったスラリーを塗布・乾燥により成形した後に焼結することによって製造されるが、得られるアルミナ焼結体（電極保護層）の気孔径及び気孔率の大きさにバラツキが発生し、ガス出力歩留まりが安定しないという問題があった。さらに電極保護層は、測定ガスを透過し、電極に到達させ、電気信号を出力させる必要があるため、所定の大きさ以上の均一な気孔率を有することが要請されるとともに、ガス中の添加剤の影響による測定電極の劣化を防止するため、所定の大きさ以下の均一な気孔径を有することが要請される。換言すれば、このような電極保護層には、多孔質体と緻密体との両方の中間に位置する物性が要請される。 In recent years, various additives such as phosphorus, zinc, magnesium or calcium have been added to engine oil and gasoline in order to improve the performance of automobiles as well as engine performance. However, when these additives are mixed in the exhaust gas, they adhere to the oxygen sensor surface and block the communication hole of the diffusion resistance layer, or adhere to the measurement electrode in the measurement chamber and deteriorate the electrode, and the sensor output is reduced. There has been a problem that it has been lowered or responsiveness has been lowered. In addition, such a porous alumina sintered body is manufactured by, for example, forming a slurry having an appropriate viscosity by applying and drying and then sintering the slurry. The resulting alumina sintered body (electrode protection) There is a problem in that the gas output yield is not stable due to variations in the pore diameter and porosity of the layer. Furthermore, the electrode protective layer needs to transmit the measurement gas, reach the electrode, and output an electrical signal. Therefore, the electrode protective layer is required to have a uniform porosity of a predetermined size or more and added to the gas. In order to prevent the measurement electrode from deteriorating due to the influence of the agent, it is required to have a uniform pore size of a predetermined size or less. In other words, such an electrode protective layer is required to have physical properties located between the porous body and the dense body.

しかしながら、多孔質のアルミナ焼結体における連通気孔の、気孔径及び気孔率等の気孔特性が所望の範囲に精密に制御されたものは未だ得られていないのが現状である。
特開平９−６８５１５号公報 However, it has not been obtained yet that the pore characteristics such as pore diameter and porosity of the continuous pores in the porous alumina sintered body are precisely controlled within a desired range.
JP-A-9-68515

本発明は、上述の問題に鑑みてなされたものであり、気体透過性の各種工業用材料、例えば、ガスセンサの測定電極用の電極保護層や集塵機におけるフィルタ等として好適に用いられる、気孔径及び気孔率等の連通気孔の特性が所望の範囲に精密に制御された多孔質のアルミナ焼結体及びその効率的な製造方法を提供することを目的とする。 The present invention has been made in view of the above-described problems, and is suitable for various gas-permeable industrial materials, for example, an electrode protective layer for a measurement electrode of a gas sensor, a filter in a dust collector, and the like. An object of the present invention is to provide a porous alumina sintered body in which the characteristics of the continuous air holes such as the porosity are precisely controlled within a desired range and an efficient manufacturing method thereof.

本発明者等は、上記目的を達成するため、鋭意研究した結果、気孔径及び気孔率等の大きさにバラツキが発生するのは、混合時における骨材及び造孔材の凝集力による分散の不安定性に起因すること及び焼結時の焼結性（例えば、焼き締まり性）の度合いの調整、制御が気孔径及び気孔率等の特性の精密制御に不可欠であること等の知見に基づき、骨材と造孔材との組み合わせとして、それぞれ均一な粒径、均一な形状の材料を用いるとともに、焼結性の度合いが異なるものを組み合わせることによって、上記目的を達成することができることを見出し本発明を完成させた。すなわち、本発明によれば、以下のアルミナ焼結体及びその製造方法が提供される。 As a result of intensive studies to achieve the above object, the present inventors have found that variations in the size of the pore diameter, porosity, etc. are caused by dispersion caused by the cohesive force of the aggregate and the pore former during mixing. Based on knowledge such as the instability and adjustment and control of the degree of sinterability during sintering (for example, shrinkage) is essential for precise control of characteristics such as pore diameter and porosity, etc. As a combination of aggregate and pore former, it is found that the above object can be achieved by using materials having uniform particle sizes and shapes and combining materials having different degrees of sinterability. Completed the invention. That is, according to the present invention, the following alumina sintered body and a manufacturing method thereof are provided.

［１］骨材としてのアルミナ粒子を造孔材の存在下で焼結することによって得られる、複数の連通気孔を有する気体透過性のアルミナ焼結体であって、前記連通気孔の平均気孔径が、４００〜１１００Åで、気孔率が、４〜１６％であり、前記連通気孔の気孔分布（気孔径の分布幅）が、３００〜１１００Åであるアルミナ焼結体。 [1] A gas-permeable alumina sintered body having a plurality of continuous air holes, obtained by sintering alumina particles as an aggregate in the presence of a pore former, and having an average pore diameter of the continuous air holes but in 400～1100A, porosity, Ri 4-16% der, the pore distribution of the communicating pores (distribution width of pore diameter), 300～1100A der Ru alumina sintered body.

［２］複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、粒径が０．２〜０．７μｍで球形度が０．７〜１．０の骨材としての第１のアルミナ粒子と、粒径が０．０１〜０．１μｍの造孔材としての第２のアルミナ粒子とを混合し、前記第１のアルミナ粒子の相互間の空隙に前記第２のアルミナ粒子の複数を埋め込むようにして、１２００〜１４００℃の温度で焼結することによって、前記連通気孔の気孔径が、４００〜１１００Åで、気孔率が、４〜１６％であるアルミナ焼結体を得るアルミナ焼結体の製造方法。 [ 2 ] A method for producing a gas-permeable alumina sintered body having a plurality of continuous air holes, wherein the aggregate has a particle size of 0.2 to 0.7 μm and a sphericity of 0.7 to 1.0. The first alumina particles and second alumina particles as a pore-forming material having a particle diameter of 0.01 to 0.1 μm are mixed, and the second alumina particles are interspersed between the first alumina particles. By sintering at a temperature of 1200 to 1400 ° C. by embedding a plurality of alumina particles, the alumina sintered body having a pore diameter of 400 to 1100 mm and a porosity of 4 to 16%. A method for producing an alumina sintered body.

［３］得られる前記アルミナ焼結体の気孔分布（気孔径の分布幅）が、３００〜１１００Åである前記［２］に記載のアルミナ焼結体の製造方法。 [ 3 ] The method for producing an alumina sintered body according to [ 2 ], wherein a pore distribution (a pore width distribution range) of the obtained alumina sintered body is 300 to 1100cm.

［４］前記第２のアルミナ粒子を、前記第１のアルミナ粒子に対して０．２〜１．５質量％の割合で混合する前記［３］に記載のアルミナ焼結体の製造方法。 [ 4 ] The method for producing an alumina sintered body according to [ 3 ], wherein the second alumina particles are mixed at a ratio of 0.2 to 1.5 mass% with respect to the first alumina particles.

［５］複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、粒径が０．２〜０．７μｍで球形度が０．７〜１．０の骨材としての第３のアルミナ粒子を、二酸化ケイ素（ＳｉＯ2）及び酸化マグネシウム（ＭｇＯ）を含む造孔材としての複合材の存在下で、１２００〜１４００℃の温度で焼結することによって、前記第３のアルミナ粒子の相互間を前記複合材の層によって結合させて、前記連通気孔の平均気孔径が、４００〜１１００Åで、気孔率が、８〜１６％であるアルミナ焼結体を得るアルミナ焼結体の製造方法。 [ 5 ] A method for producing a gas-permeable alumina sintered body having a plurality of continuous air holes, wherein the aggregate has a particle size of 0.2 to 0.7 μm and a sphericity of 0.7 to 1.0. The third alumina particles are sintered at a temperature of 1200 to 1400 ° C. in the presence of a composite material as a pore former containing silicon dioxide (SiO 2 ) and magnesium oxide (MgO). The alumina particles are bonded to each other by the composite layer to obtain an alumina sintered body having an average pore diameter of 400 to 1100 mm and a porosity of 8 to 16%. Body manufacturing method.

［６］前記複合材を、前記第３のアルミナ粒子に対して０．０２〜２質量％の割合で混合する前記［５］に記載のアルミナ焼結体の製造方法。 [ 6 ] The method for producing an alumina sintered body according to [ 5 ], wherein the composite material is mixed at a ratio of 0.02 to 2 mass% with respect to the third alumina particles.

［７］得られる前記アルミナ焼結体の気孔分布（気孔径の分布幅）が、３００〜１１００Åである前記［５］又は［６］に記載のアルミナ焼結体の製造方法。 [ 7 ] The method for producing an alumina sintered body according to [ 5 ] or [ 6 ], wherein a pore distribution (a pore width distribution range) of the obtained alumina sintered body is 300 to 1100cm.

［８］複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、粒径が０．３〜１．０μｍで球形度が０．７〜１．０の骨材としての第４のアルミナ粒子と、粒径が０．２〜０．８μｍの造孔材としての第５のアルミナ粒子とを混合し、前記第４のアルミナ粒子間の空隙に前記第５のアルミナ粒子を嵌め込むようにして、前記１２００〜１４００℃の温度で焼結することによって、前記連通気孔の平均気孔径が、４００〜１１００Åで、気孔率が、８〜１６％であるアルミナ焼結体を得るアルミナ焼結体の製造方法。 [ 8 ] A method for producing a gas-permeable alumina sintered body having a plurality of continuous air holes, wherein the aggregate has a particle size of 0.3 to 1.0 μm and a sphericity of 0.7 to 1.0. The fourth alumina particles and the fifth alumina particles as the pore former having a particle diameter of 0.2 to 0.8 μm are mixed, and the fifth alumina particles are inserted into the gaps between the fourth alumina particles. To obtain an alumina sintered body having an average pore diameter of 400 to 1100 mm and a porosity of 8 to 16% by sintering at a temperature of 1200 to 1400 ° C. A method for producing a sintered body.

［９］得られる前記アルミナ焼結体の気孔分布（気孔径の分布幅）が、３００〜１１００Åである前記［８］に記載のアルミナ焼結体の製造方法。 [ 9 ] The method for producing an alumina sintered body according to [ 8 ], wherein a pore distribution (a pore width distribution range) of the obtained alumina sintered body is 300 to 1100cm.

［１０］前記第５のアルミナ粒子を、前記第４のアルミナ粒子に対して５０〜９５質量％の割合で混合する前記［８］又は［９］に記載のアルミナ焼結体の製造方法。 [1 0 ] The method for producing an alumina sintered body according to [ 8 ] or [ 9 ], wherein the fifth alumina particles are mixed at a ratio of 50 to 95% by mass with respect to the fourth alumina particles.

本発明によって、気体透過性の各種工業用材料、例えば、ガスセンサの測定電極用の電極保護層や集塵機におけるフィルタ等として好適に用いられる、気孔径及び気孔率等の連通気孔の特性が所望の範囲に精密に制御された多孔質のアルミナ焼結体及びその効率的な製造方法が提供される。 According to the present invention, various gas-permeable industrial materials, for example, electrode protective layers for measuring electrodes of gas sensors and filters for dust collectors, etc., the desired range of characteristics of continuous vents such as pore diameter and porosity, etc. A porous alumina sintered body precisely controlled and an efficient manufacturing method thereof are provided.

以下、本発明のアルミナ焼結体及びその製造方法の実施の形態を図面を参照しながら詳細に説明する。 DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an alumina sintered body and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings.

本発明のアルミナ焼結体の実施の形態は、骨材としてのアルミナ粒子を造孔材の存在下で焼結することによって得られる、複数の連通気孔を有する気体透過性のアルミナ焼結体であって、連通気孔の平均気孔径が、４００〜１１００Å、好ましくは、５００〜９００Åで、気孔率が、４〜１６％、好ましくは、９〜１４％であることを特徴とするものである。気孔径が、４００〜１１００Åの範囲を外れると、例えば、ガスセンサの測定電極用の電極保護層として用いた場合、排気ガス中に混入するガソリン添加剤の影響によって耐久性が劣化し、ガス出力低下率（％）が増大する。気孔率が、４〜１６％の範囲を外れると、例えば、電極保護層として用いた場合、測定電極へのガスの流入量が変動して、ガス出力歩留まりを不安定化させる。 An embodiment of the alumina sintered body of the present invention is a gas-permeable alumina sintered body having a plurality of continuous air holes, obtained by sintering alumina particles as an aggregate in the presence of a pore former. In addition, the average pore diameter of the continuous ventilation holes is 400 to 1100 mm, preferably 500 to 900 mm, and the porosity is 4 to 16%, preferably 9 to 14%. When the pore diameter is outside the range of 400 to 1100 mm, for example, when used as an electrode protective layer for a measurement electrode of a gas sensor, the durability deteriorates due to the influence of gasoline additives mixed in the exhaust gas, and the gas output decreases. The rate (%) increases. When the porosity is out of the range of 4 to 16%, for example, when used as an electrode protective layer, the amount of gas flowing into the measurement electrode varies, destabilizing the gas output yield.

本実施の形態においては、連通気孔の気孔分布（気孔径の分布幅）は、３００〜１１００Åであることが好ましく、５００〜９００Åであることがさらに好ましい。１１００Åの範囲を外れると、ガス出力低下率（％）が増大するとともに、ガス出力歩留まりを不安定化させることがある。 In the present embodiment, the pore distribution (pore diameter distribution width) of the continuous air holes is preferably 300 to 1100 cm, and more preferably 500 to 900 cm. If it is out of the range of 1100%, the gas output reduction rate (%) increases and the gas output yield may become unstable.

本実施の形態に用いられるアルミナ粒子、造孔材及び焼結方法については、後述するアルミナ焼結体の製造方法のところで説明する。 The alumina particles, the pore former and the sintering method used in the present embodiment will be described in the method for producing an alumina sintered body described later.

本実施の形態のアルミナ焼結体の形状としては特に制限はないが、例えば、厚さが、１５〜１００μｍの薄膜状又は層状、ブロック形状等を挙げることができる。 Although there is no restriction | limiting in particular as a shape of the alumina sintered compact of this Embodiment, For example, the thin film shape or layer shape whose thickness is 15-100 micrometers, a block shape etc. can be mentioned.

以下、本発明のアルミナ焼結体の製造方法（第１〜第３の製造方法）について説明する。（球形度は、楕円の短径をｒ１、長径をｒ２とした時、ｒ１／ｒ２を球形度とする。ｒ１／ｒ２＝１は真球をあらわす。以下同じ。） Hereinafter, the manufacturing method (1st-3rd manufacturing method) of the alumina sintered compact of this invention is demonstrated. (The sphericity is r1 / r2 when the minor axis of the ellipse is r1 and the major axis is r2. R1 / r2 = 1 represents a true sphere. The same applies hereinafter.)

図１に示すように、第１の製造方法（以下、「粒子間埋込法」ということがある）は、複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、粒径が０．２〜０．７μｍ、好ましくは０．３〜０．５μｍで、球形度が０．７〜１．０、好ましくは、０．８〜１．０の骨材としての第１のアルミナ粒子１と、粒径が０．０１〜０．１μｍ、好ましくは０．０１〜０．０５μｍの造孔材としての第２のアルミナ粒子２とを混合し、第１のアルミナ粒子１の相互間の空隙に第２のアルミナ粒子２の複数を埋め込むようにして、１２００〜１４００℃、好ましくは１３００〜１３８０℃の温度で焼結することによって、連通気孔３の気孔径が、４００〜１１００Å、好ましくは５００〜９００Åで、気孔率が、４〜１６％、好ましくは９〜１４％であるアルミナ焼結体１０を得ることを特徴とする。 As shown in FIG. 1, the first manufacturing method (hereinafter sometimes referred to as “interparticle embedding method”) is a method of manufacturing a gas-permeable alumina sintered body having a plurality of continuous air holes. The particle size is 0.2 to 0.7 μm, preferably 0.3 to 0.5 μm, and the sphericity is 0.7 to 1.0, preferably 0.8 to 1.0. 1 alumina particles 1 and second alumina particles 2 as a pore-forming material having a particle size of 0.01 to 0.1 μm, preferably 0.01 to 0.05 μm, are mixed, and the first alumina particles 1 are mixed. By embedding a plurality of second alumina particles 2 in the gaps between them, sintering is performed at a temperature of 1200 to 1400 ° C., preferably 1300 to 1380 ° C., so that the pore diameter of the continuous air holes 3 is 400 to 400 ° C. 1100cm, preferably 500-900mm, porosity 4-16%, preferred Ku is characterized by obtaining an alumina sintered body 10 is 9-14%.

第１のアルミナ粒子１の粒径が０．２〜０．７μｍの範囲を外れ、また球形度が０．７〜１．０の範囲を外れると、第１のアルミナ粒子１の凝集性が増大、もしくは、焼結度が甘くなり、焼結によって得られるアルミナ焼結体１０の気孔径及び気孔率の大きさにバラツキを発生させることになる。 When the particle diameter of the first alumina particles 1 is out of the range of 0.2 to 0.7 μm and the sphericity is out of the range of 0.7 to 1.0, the cohesiveness of the first alumina particles 1 is increased. Alternatively, the degree of sintering becomes sweet, and variations occur in the pore diameter and the porosity of the alumina sintered body 10 obtained by sintering.

第２のアルミナ粒子２の粒径が０．０１〜０．１μｍの範囲を外れると、第２のアルミナ粒子２の焼結時の焼結性の程度が好ましい範囲を外れることになり、焼結によって得られるアルミナ焼結体１０の気孔径及び気孔率の特性にバラツキを発生させることになる。この意味で、第２のアルミナ粒子２の場合も、球形度が０．７〜１．０であることが好ましく、０．８〜１．０であることがさらに好ましい。また、焼結温度が、１２００〜１４００℃の範囲を外れると、焼成不足もしくは焼成過度となり必要とする気孔特性を得ることができない。 When the particle diameter of the second alumina particles 2 is out of the range of 0.01 to 0.1 μm, the degree of sinterability at the time of sintering the second alumina particles 2 is out of the preferable range, and the sintering is performed. As a result, variation occurs in the pore diameter and porosity characteristics of the alumina sintered body 10 obtained. In this sense, also in the case of the second alumina particles 2, the sphericity is preferably 0.7 to 1.0, and more preferably 0.8 to 1.0. On the other hand, if the sintering temperature is outside the range of 1200 to 1400 ° C., the necessary pore characteristics cannot be obtained due to insufficient firing or excessive firing.

本発明においては、得られるアルミナ焼結体１０の気孔分布（気孔径の分布幅）は、３００〜１１００Åであることが好ましく、５００〜１１００Åであることがさらに好ましい。この範囲を外れると、汚染物質（ガソリン添加剤等）をトラップする機能の低下、ガスの通気性低下が発生する。 In the present invention, the pore distribution (pore diameter distribution width) of the obtained alumina sintered body 10 is preferably 300 to 1100%, and more preferably 500 to 1100%. Outside this range, the function of trapping pollutants (gasoline additives, etc.) and the gas permeability are reduced.

第１のアルミナ粒子１及び第２のアルミナ粒子２としては、上述の粒径及び球形度の範囲を満たし、均一な粒径で均一な形状のものであれば特に制限はないが、例えば、α−アルミナ、γ−アルミナ等を挙げることができる。 The first alumina particles 1 and the second alumina particles 2 are not particularly limited as long as they satisfy the above-mentioned range of particle diameter and sphericity and have a uniform particle diameter and a uniform shape. -Alumina, γ-alumina and the like can be mentioned.

第１のアルミナ粒子１と第２のアルミナ粒子２とを混合し、第１のアルミナ粒子１の相互間の空隙に第２のアルミナ粒子２の複数を埋め込むための具体的な方法としては、例えば、混合アルミナを有機バインダー液に分散させたスラリーを塗布したり、混合アルミナを圧粉成形することを挙げることができる。この場合、第１のアルミナ粒子１と第２のアルミナ粒子２との混合割合は、第２のアルミナ粒子２を第１のアルミナ粒子１に対して、０．２〜１．５質量％混合することが好ましく、０．３〜１．０質量％混合することがさらに好ましい。 As a specific method for mixing the first alumina particles 1 and the second alumina particles 2 and embedding a plurality of the second alumina particles 2 in the gaps between the first alumina particles 1, for example, The slurry in which the mixed alumina is dispersed in the organic binder liquid can be applied or the mixed alumina can be compacted. In this case, the mixing ratio of the first alumina particles 1 and the second alumina particles 2 is such that 0.2 to 1.5 mass% of the second alumina particles 2 is mixed with the first alumina particles 1. It is preferable to mix 0.3 to 1.0% by mass.

焼結方法としては特に制限はないが、例えば、成形膜もしくは圧粉成形体を大気中で加熱することを挙げることができる。 Although there is no restriction | limiting in particular as a sintering method, For example, heating a shaping | molding film | membrane or a compacting body in air | atmosphere can be mentioned.

本発明においては、粒径、球形度、気孔径、気孔率、気孔分布（気孔径の分布幅）の測定は、それぞれ、以下のようにして行うことができる。
粒径（レーザー回折式粒度分布測定装置使用）
球形度（ＳＥＭにて粒子の長径、短径を測定）
平均気孔径（水銀圧入式細孔分布測定装置使用）
気孔率（水銀圧入式細孔分布測定装置使用）
気孔分布（気孔径の分布幅）（水銀圧入式細孔分布測定装置使用） In the present invention, the particle size, sphericity, pore diameter, porosity, and pore distribution (pore diameter distribution width) can be measured as follows.
Particle size (using laser diffraction particle size distribution analyzer)
Sphericality (measures the long and short diameters of particles with SEM)
Average pore size (using mercury intrusion type pore distribution measuring device)
Porosity (use of mercury intrusion type pore distribution measuring device)
Pore distribution (distribution range of pore diameter) (using mercury intrusion type pore distribution measuring device)

図２に示すように、第２の製造方法（以下、「粒界結合法」ということがある）は、複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、粒径が０．２〜０．７μｍ、好ましくは０．３〜０．５μｍで、球形度が０．７〜１．０、好ましくは０．８〜１．０の骨材としての第３のアルミナ粒子４を、二酸化ケイ素（ＳｉＯ2）及び酸化マグネシウム（ＭｇＯ）を含む造孔材としての複合材５の存在下で、１２００〜１４００℃、好ましくは、１３００〜１３８０℃の温度で焼結することによって、第３のアルミナ粒子４の相互間を複合材５の層（複合材結合層６）によって結合させて、連通気孔７の気孔径が、４００〜１１００Å、好ましくは５００〜９００Åで、気孔率が、４〜１６％、好ましくは９〜１４％であるアルミナ焼結体２０を得ることを特徴とする。 As shown in FIG. 2, the second production method (hereinafter sometimes referred to as “grain boundary bonding method”) is a method of producing a gas-permeable alumina sintered body having a plurality of continuous air holes, Third as an aggregate having a particle size of 0.2 to 0.7 μm, preferably 0.3 to 0.5 μm and a sphericity of 0.7 to 1.0, preferably 0.8 to 1.0. The alumina particles 4 are sintered at a temperature of 1200 to 1400 ° C., preferably 1300 to 1380 ° C. in the presence of the composite material 5 as a pore former containing silicon dioxide (SiO 2 ) and magnesium oxide (MgO). Accordingly, the third alumina particles 4 are bonded to each other by the layer of the composite material 5 (composite material bonding layer 6), and the pore diameter of the continuous air holes 7 is 400 to 1100 mm, preferably 500 to 900 mm. The rate is 4-16%, preferably 9-14% Alumina sintered body 20 is obtained.

第３のアルミナ粒子４の粒径が０．２〜０．７μｍの範囲を外れ、また球形度が０．７〜１．０の範囲を外れると、第３のアルミナ粒子４の凝集性が増大、もしくは、焼結性が甘くなり、焼結によって得られるアルミナ焼結体２０の気孔径及び気孔率の大きさにバラツキを発生させることになる。 When the particle diameter of the third alumina particles 4 is out of the range of 0.2 to 0.7 μm and the sphericity is out of the range of 0.7 to 1.0, the cohesiveness of the third alumina particles 4 increases. Or, the sinterability becomes sweet, and the pore diameter and the porosity of the alumina sintered body 20 obtained by sintering are varied.

複合材５としては、二酸化ケイ素（ＳｉＯ2）及び酸化マグネシウム（ＭｇＯ）を含むものであれば特に制限はないが、例えば、ＳｉＯ2＋ＭｇＯ＋ＣａＯ、ＳｉＯ2＋ＭｇＯ＋ＢａＯを挙げることができる。複合材５は、第３のアルミナ粒子４に対して０．０２〜２質量％混合することが好ましく、０．０５〜１質量％混合することがさらに好ましい。 The composite material 5 is not particularly limited as long as it contains silicon dioxide (SiO 2 ) and magnesium oxide (MgO), and examples thereof include SiO 2 + MgO + CaO and SiO 2 + MgO + BaO. The composite material 5 is preferably mixed in an amount of 0.02 to 2 mass%, more preferably 0.05 to 1 mass%, with respect to the third alumina particles 4.

第２の発明においては、得られるアルミナ焼結体２０の気孔分布（気孔径の分布幅）は、４００〜１１００Åであることが好ましく、５００〜９００Åであることがさらに好ましい。この範囲を外れると、汚染物質（ガソリン添加剤等）をトラップする機能の低下、ガスの通気性低下が発生する。 In the second invention, the pore distribution (pore diameter distribution width) of the alumina sintered body 20 to be obtained is preferably 400 to 1100 and more preferably 500 to 900. Outside this range, the function of trapping pollutants (gasoline additives, etc.) and the gas permeability are reduced.

第３のアルミナ粒子４としては、上述の粒径及び球形度の範囲を満たし、均一な粒径で均一な形状のものであれば特に制限はないが、例えば、α−アルミナ、γ−アルミナ等を挙げることができる。 The third alumina particle 4 is not particularly limited as long as it satisfies the above range of particle size and sphericity and has a uniform particle size and a uniform shape. For example, α-alumina, γ-alumina, etc. Can be mentioned.

第３のアルミナ粒子４と複合材５とを混合し、第３のアルミナ粒子４の相互間を複合材５の層（複合材結合層６）によって結合させるための具体的な方法としては、例えば、アルミナと複合材成分を混合したものを有機バインダー液に分散させたスラリーを塗布したりアルミナと複合材成分を混合したものを圧粉成形することを挙げることができる。 As a specific method for mixing the third alumina particles 4 and the composite material 5 and bonding the third alumina particles 4 to each other by the layer of the composite material 5 (composite material bonding layer 6), for example, Further, it is possible to apply a slurry in which a mixture of alumina and a composite material component is dispersed in an organic binder liquid, or to compact a mixture of alumina and a composite material component.

焼結方法としては特に制限はないが、例えば、塗布膜、もしくは圧粉成形体を大気中で加熱することを挙げることができる。 Although there is no restriction | limiting in particular as a sintering method, For example, heating a coating film or a compacting body in air | atmosphere can be mentioned.

第２の製造方法において、粒径、球形度、気孔径、気孔率、気孔分布（気孔径の分布幅）の測定は、それぞれ、第１の製造方法（「粒子間埋込法」）の場合と同様にして行うことができる。 In the second manufacturing method, the measurement of particle size, sphericity, pore diameter, porosity, and pore distribution (pore diameter distribution width) is performed in the case of the first manufacturing method (“interparticle embedding method”). It can be performed in the same way.

図３に示すように、第３の製造方法（以下、「骨材ブレンド法」ということがある）は、複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、粒径が０．３〜１．０μｍ、好ましくは０．４〜０．７μｍで、球形度が０．７〜１．０、好ましくは０．８〜１．０の骨材としての第４のアルミナ粒子８と、粒径が０．２〜０．８μｍ、好ましくは０．３〜０．５μｍの造孔材としての第５のアルミナ粒子９とを混合し、第４のアルミナ粒子８間の空隙に第５のアルミナ粒子９を嵌め込むようにして、１２００〜１４００℃の温度で焼結することによって、連通気孔１１の気孔径が、４００〜１１００Å、好ましくは、５００〜９００Åで、気孔率が、４〜１６％、好ましくは、９〜１４％であるアルミナ焼結体３０を得ることを特徴とする。 As shown in FIG. 3, the third production method (hereinafter sometimes referred to as “aggregate blending method”) is a method of producing a gas-permeable alumina sintered body having a plurality of continuous air holes, A fourth particle as an aggregate having a particle size of 0.3 to 1.0 μm, preferably 0.4 to 0.7 μm and a sphericity of 0.7 to 1.0, preferably 0.8 to 1.0. Alumina particles 8 are mixed with fifth alumina particles 9 as a pore former having a particle size of 0.2 to 0.8 μm, preferably 0.3 to 0.5 μm. Sintering at a temperature of 1200 to 1400 ° C. so that the fifth alumina particles 9 are fitted in the voids, the pore diameter of the continuous air holes 11 is 400 to 1100 mm, preferably 500 to 900 mm, and the porosity is An alumina sintered body 30 having 4 to 16%, preferably 9 to 14% is obtained. It is characterized in.

第４のアルミナ粒子８の粒径が０．３〜１．０μｍの範囲を外れ、また球形度が０．７〜１．０の範囲を外れると、第４のアルミナ粒子８の凝集性が増大、もしくは、焼結度が甘くなり、焼結によって得られるアルミナ焼結体３０の気孔径及び気孔率等の大きさにバラツキを発生させることになる。 If the particle diameter of the fourth alumina particles 8 is out of the range of 0.3 to 1.0 μm and the sphericity is out of the range of 0.7 to 1.0, the cohesiveness of the fourth alumina particles 8 increases. Alternatively, the degree of sintering becomes sweet, and the alumina sintered body 30 obtained by sintering has a variation in the pore diameter, the porosity, and the like.

第５のアルミナ粒子９の粒径が０．２〜０．８μｍの範囲を外れると、第５のアルミナ粒子９の焼結時の焼結性の程度が好ましい範囲を外れることになり、焼結によって得られるアルミナ焼結体３０の気孔径及び気孔率等の特性にバラツキを発生させることになる。この意味で、第５のアルミナ粒子９の場合も、球形度が０．７〜１．０であることが好ましく、０．８〜１．０であることがさらに好ましい。また、焼結温度が、１２００〜１４００℃の範囲を外れると、焼成不足もしくは焼成過度となり必要とする気孔特性を得ることができない。 If the particle diameter of the fifth alumina particles 9 is out of the range of 0.2 to 0.8 μm, the degree of sinterability at the time of sintering the fifth alumina particles 9 is out of the preferred range, and the sintering is performed. As a result, variations in characteristics such as the pore diameter and porosity of the alumina sintered body 30 obtained by the above-described method occur. In this sense, in the case of the fifth alumina particles 9, the sphericity is preferably 0.7 to 1.0, and more preferably 0.8 to 1.0. On the other hand, if the sintering temperature is outside the range of 1200 to 1400 ° C., the necessary pore characteristics cannot be obtained due to insufficient firing or excessive firing.

第３の発明においては、得られるアルミナ焼結体３０の気孔分布（気孔径の分布幅）は、４００〜１１００Åであることが好ましく、５００〜９００Åであることがさらに好ましい。この範囲を外れると、汚染物質（ガソリン添加剤等）をトラップする機能の低下、ガスの通気性低下が発生する。 In the third invention, the pore distribution (pore diameter distribution width) of the alumina sintered body 30 to be obtained is preferably 400 to 1100 and more preferably 500 to 900. Outside this range, the function of trapping pollutants (gasoline additives, etc.) and the gas permeability are reduced.

第４のアルミナ粒子８及び第５のアルミナ粒子９としては、上述の粒径及び球形度の範囲を満たし、均一な粒径で均一な形状のものであれば特に制限はないが、例えば、α−アルミナ、γ−アルミナ等を挙げることができる。 The fourth alumina particles 8 and the fifth alumina particles 9 are not particularly limited as long as they satisfy the above-mentioned ranges of particle diameter and sphericity and have a uniform particle diameter and a uniform shape. -Alumina, γ-alumina and the like can be mentioned.

第４のアルミナ粒子８と第５のアルミナ粒子９とを混合し、第４のアルミナ粒子８間の空隙に第５のアルミナ粒子９を嵌め込むようにするための具体的な方法としては、例えば、混合アルミナを有機バインダー液に分散させたスラリーを塗布したり、混合アルミナを圧粉成形することを挙げることができる。この場合、第４のアルミナ粒子８と第５のアルミナ粒子９との混合割合は、第５のアルミナ粒子９を第４のアルミナ粒子８に対して、５０〜９５質量％混合することが好ましく、５０〜９０質量％混合することがさらに好ましい。 As a specific method for mixing the fourth alumina particles 8 and the fifth alumina particles 9 and fitting the fifth alumina particles 9 into the gaps between the fourth alumina particles 8, for example, The slurry in which the mixed alumina is dispersed in the organic binder liquid can be applied or the mixed alumina can be compacted. In this case, the mixing ratio of the fourth alumina particles 8 and the fifth alumina particles 9 is preferably 50 to 95% by mass of the fifth alumina particles 9 with respect to the fourth alumina particles 8. It is more preferable to mix 50 to 90% by mass.

焼結方法としては特に制限はないが、例えば、塗布膜、もしくは圧粉成形体を大気中で加熱することを挙げることができる。 Although there is no restriction | limiting in particular as a sintering method, For example, heating a coating film or a compacting body in air | atmosphere can be mentioned.

第３の製造方法において、粒径、球形度、気孔径、気孔率、気孔分布（気孔径の分布幅）の測定は、それぞれ、第１の製造方法（「粒子間埋込法」）の場合と同様にして行うことができる。 In the third production method, the measurement of particle size, sphericity, pore diameter, porosity, and pore distribution (pore size distribution width) is performed in the case of the first production method (“interparticle embedding method”). It can be performed in the same way.

なお、第１の製造方法（「粒子間埋込法」）と、第３の製造方法（「骨材ブレンド法」）との相違は、アルミナ粒子２とアルミナ粒子９のサイズである。 The difference between the first manufacturing method (“interparticle embedding method”) and the third manufacturing method (“aggregate blending method”) is the sizes of the alumina particles 2 and the alumina particles 9.

以下、本発明を実施例を挙げて具体的に説明するが、本発明はこれら実施例に限定されるものではない。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples.

（実施例１）
第１の製造方法の実施例
第１のアルミナ粒子１からなる原料粉末に、分散媒（例えば、エタノール）、分散剤、第２のアルミナ粒子２を含むスラリーを添加し、予備混合した後、予め、溶剤（例えばターピネオール）に有機バインダー（例えばエチルセルロース）及び可塑剤を溶かした液（以下「有機バインダー液」という）を追加して更に混合後、分散媒の除去及び溶剤の追加により粘度を調整することにより得られたペーストを塗布または印刷により膜状成形体を作製し、これを焼成する。 Example 1
Example of First Production Method After adding a slurry containing a dispersion medium (for example, ethanol), a dispersant, and second alumina particles 2 to the raw material powder made of the first alumina particles 1, pre-mixing, After adding a liquid (hereinafter referred to as “organic binder liquid”) in which an organic binder (for example, ethyl cellulose) and a plasticizer are dissolved in a solvent (for example, terpineol) and further mixing, the viscosity is adjusted by removing the dispersion medium and adding the solvent. A film-like molded body is produced by applying or printing the paste obtained in this way, and this is fired.

（実施例２）
第２の製造方法の実施例
第３のアルミナ粒子４からなる原料粉末に、分散媒（例えば、エタノール）、分散剤、ＳｉＯ2源（例えばシリカゾル）、ＭｇＯ源（例えば、酢酸マグネシウム）を添加し、以下上記の第１の製造方法と同じ方法で焼結体を得る。 (Example 2)
Example of Second Production Method A dispersion medium (for example, ethanol), a dispersant, a SiO 2 source (for example, silica sol), and a MgO source (for example, magnesium acetate) are added to the raw material powder composed of the third alumina particles 4. Then, a sintered body is obtained by the same method as the first manufacturing method described above.

（実施例３）
第３の製造方法の実施例
第４のアルミナ粒子８からなる原料粉末と、第５のアルミナ粒子９からなる原料粉末との混合粉末に分散媒（例えば、エタノール）、分散剤を添加し、以下上記の第１の製造方法と同じ方法で焼結体を得る。 (Example 3)
Example of Third Manufacturing Method A dispersion medium (for example, ethanol) and a dispersing agent are added to a mixed powder of a raw material powder made of the fourth alumina particles 8 and a raw material powder made of the fifth alumina particles 9, and the following A sintered body is obtained by the same method as the first manufacturing method.

（比較例１）
従来の製造方法の比較例
従来のアルミナ粒子からなる原料粉末と、アルミニウム塩（例えば水酸化アルミニウム）との混合粉末に分散媒（例えば、エタノール）、分散剤を添加し、以下上記の第１の製造方法と同じ方法で焼結体を得る。 (Comparative Example 1)
Comparative Example of Conventional Manufacturing Method A dispersion medium (for example, ethanol) and a dispersing agent are added to a mixed powder of a raw material powder made of conventional alumina particles and an aluminum salt (for example, aluminum hydroxide). A sintered body is obtained by the same method as the manufacturing method.

（評価）
実施例１〜３及び比較例１で用いた材料（骨材及び造孔材）の粒径、形状、混合割合、焼結温度並びに得られたアルミナ焼結体の気孔径、気孔率及び気孔分布（気孔径の分布幅）を表１に示す。表１に示すように、実施例１〜３で得られたアルミナ焼結体の方が、比較例１で得られたアルミナ焼結体よりも、気孔径、気孔率及び気孔分布（気孔径の分布幅）において精密に制御されていることがわかる。 (Evaluation)
The particle diameter, shape, mixing ratio, sintering temperature of the materials (aggregate and pore former) used in Examples 1 to 3 and Comparative Example 1, and the pore diameter, porosity and pore distribution of the obtained alumina sintered body (Pore diameter distribution width) is shown in Table 1. As shown in Table 1, the alumina sintered bodies obtained in Examples 1 to 3 were more porous than the alumina sintered body obtained in Comparative Example 1, and the porosity and pore distribution (of the pore diameter). It can be seen that the distribution width is precisely controlled.

Figure 0004498727
Figure 0004498727

図４に、実施例１で得られたアルミナ焼結体と、比較例１で得られたアルミナ焼結体との気孔分布（気孔径の分布幅）の比較を示す。図４に示すように、実施例１で得られたアルミナ焼結体の気孔分布（気孔径の分布幅）は、比較例１で得られたアルミナ焼結体の気孔分布（気孔径の分布幅）の約１／２であり、より精密に制御されていることがわかる。 FIG. 4 shows a comparison of pore distribution (pore diameter distribution width) between the alumina sintered body obtained in Example 1 and the alumina sintered body obtained in Comparative Example 1. As shown in FIG. 4, the pore distribution (pore diameter distribution width) of the alumina sintered body obtained in Example 1 is the pore distribution (pore diameter distribution width) of the alumina sintered body obtained in Comparative Example 1. It can be seen that the control is more precise.

図５に、実施例１で得られたアルミナ焼結体と、比較例１で得られたアルミナ焼結体とを、それぞれガスセンサ（ＮＯｘガスセンサ）の測定電極用の電極保護層として用いた場合の、バインダロット変動、印刷経時変動、調合ロット変動及び原料ロット変動の比較を示す。図５に示すように、実施例１で得られたアルミナ焼結体の方が、比較例１で得られたものよりも、ＮＯｘガス出力変動（μＡ）が小さいことがわかる。なお、ガスセンサは、以下のように作製した。 FIG. 5 shows a case where the alumina sintered body obtained in Example 1 and the alumina sintered body obtained in Comparative Example 1 are used as electrode protective layers for measurement electrodes of a gas sensor (NOx gas sensor), respectively. Comparison of binder lot fluctuation, printing time fluctuation, blending lot fluctuation and raw material lot fluctuation is shown. As shown in FIG. 5, it can be seen that the alumina sintered body obtained in Example 1 has smaller NOx gas output fluctuation (μA) than that obtained in Comparative Example 1. In addition, the gas sensor was produced as follows.

ジルコニア（固体電解質）シートＳ１の上面にポンプ電極を形成するペーストを印刷し、下面にポンプ電極及び補助ポンプ電極をそれぞれ形成するペースを印刷する。また、ジルコニア（固体電解質）シートＳ３の上面に測定電極を形成するペーストを印刷した後、実施例１および比較例１で得られたペーストを印刷する。
次に、印刷後のジルコニア（固体電解質）シートＳ１とジルコニア（固体電解質）シートＳ３との間に空間を設けるためパンチングを施したジルコニア（固体電解質）シートＳ２を挟み込むように積層し、切断加工後、焼成する。ただし、シートＳ２の一部分に有機ペースト（バインダー液）を塗布・乾燥した後、焼成工程で、本有機ペーストを除去することにより、シートＳ１とシートＳ２の間およびシートＳ２とＳ３の間にガス経路が形成される。 The paste for forming the pump electrode is printed on the upper surface of the zirconia (solid electrolyte) sheet S1, and the pace for forming the pump electrode and the auxiliary pump electrode is printed on the lower surface. Moreover, after printing the paste which forms a measurement electrode on the upper surface of the zirconia (solid electrolyte) sheet | seat S3, the paste obtained in Example 1 and Comparative Example 1 is printed.
Next, the printed zirconia (solid electrolyte) sheet S1 and the zirconia (solid electrolyte) sheet S3 are laminated so as to sandwich the punched zirconia (solid electrolyte) sheet S2 so as to provide a space between them, and after cutting , Fire. However, after applying and drying an organic paste (binder liquid) on a part of the sheet S2, the organic paste is removed in a firing step, whereby a gas path is formed between the sheets S1 and S2 and between the sheets S2 and S3. Is formed.

図６に、実施例１で得られたアルミナ焼結体と、比較例１で得られたアルミナ焼結体とを、それぞれ図５に示す場合と同様の構成からなるガスセンサ（ＮＯｘガスセンサ）の測定電極用の電極保護層として用いた場合の、９５０℃連続耐久試験の比較を示す。図６に示すように、実施例１で得られたアルミナ焼結体の方が、比較例１で得られたものよりも、ＮＯｘガス感度変化率（％）が小さいことがわかる。 FIG. 6 shows the measurement of a gas sensor (NOx gas sensor) having the same structure as that shown in FIG. 5 for the alumina sintered body obtained in Example 1 and the alumina sintered body obtained in Comparative Example 1. The comparison of a 950 degreeC continuous durability test at the time of using as an electrode protective layer for electrodes is shown. As shown in FIG. 6, it can be seen that the alumina sintered body obtained in Example 1 has a smaller NOx gas sensitivity change rate (%) than that obtained in Comparative Example 1.

本発明のアルミナ焼結体及びその製造方法は、気体透過性の各種工業用材料、例えば、ガスセンサの測定電極用の電極保護層や集塵機におけるフィルタ等として好適に利用される。 The alumina sintered body and the production method thereof of the present invention are suitably used as various gas permeable industrial materials, for example, an electrode protective layer for a measurement electrode of a gas sensor or a filter in a dust collector.

本発明（第１の製造方法（「粒子間埋込法」））の実施の形態における骨材と造孔材との挙動を模式的に示す説明図である。It is explanatory drawing which shows typically the behavior of the aggregate and pore former in embodiment of this invention (1st manufacturing method ("interparticle embedding method")). 本発明（第２の製造方法（「粒界結合法」））の実施の形態における骨材と造孔材との挙動を模式的に示す説明図である。It is explanatory drawing which shows typically the behavior of the aggregate and the pore former in the embodiment of the present invention (second production method (“grain boundary bonding method”)). 本発明（第３の製造方法（「骨材ブレンド法」））の実施の形態における骨材と造孔材との挙動を模式的に示す説明図である。It is explanatory drawing which shows typically the behavior of the aggregate and pore former in embodiment of this invention (3rd manufacturing method ("aggregate blend method")). 実施例１で得られたアルミナ焼結体と、比較例１で得られたアルミナ焼結体との気孔分布（気孔径の分布幅）の比較を示すグラフである。4 is a graph showing a comparison of pore distribution (pore diameter distribution width) between the alumina sintered body obtained in Example 1 and the alumina sintered body obtained in Comparative Example 1. FIG. 実施例１で得られたアルミナ焼結体と、比較例１で得られたアルミナ焼結体とを、それぞれガスセンサ（ＮＯｘガスセンサ）の測定電極用の電極保護層として用いた場合の、バインダロット変動、印刷経時変動、調合ロット変動及び原料ロット変動の比較を示すグラフである。Binder lot fluctuation when the alumina sintered body obtained in Example 1 and the alumina sintered body obtained in Comparative Example 1 were used as electrode protective layers for measurement electrodes of a gas sensor (NOx gas sensor), respectively. It is a graph which shows the comparison of printing temporal fluctuation, mixing lot fluctuation, and raw material lot fluctuation. 実施例１で得られたアルミナ焼結体と、比較例１で得られたアルミナ焼結体とを、それぞれガスセンサ（ＮＯｘガスセンサ）の測定電極用の電極保護層として用いた場合の、９５０℃連続耐久試験の比較を示すグラフである。950 ° C. continuous when the alumina sintered body obtained in Example 1 and the alumina sintered body obtained in Comparative Example 1 are used as electrode protective layers for measurement electrodes of a gas sensor (NOx gas sensor), respectively. It is a graph which shows the comparison of an endurance test. 従来の電極保護層を備えたＮＯｘガスセンサを９５０℃の温度で１００時間連続して運転した場合の高温耐久性（補助ポンプ電極から揮発、飛散した金（Ａｕ）による被毒の程度）の尺度となる、電極保護層の気孔径（Å）とＮＯｘガス出力低下率（％）との関係を示すグラフである。A measure of high-temperature durability (degree of poisoning due to gold (Au) volatilized and scattered from the auxiliary pump electrode) when a conventional NOx gas sensor having an electrode protective layer is continuously operated at a temperature of 950 ° C. for 100 hours; It is a graph which shows the relationship between the pore diameter (Å) of an electrode protective layer, and NOx gas output fall rate (%).

符号の説明Explanation of symbols

１…第１のアルミナ粒子、２…第２のアルミナ粒子、３…連通気孔、４…第３のアルミナ粒子、５…複合材、６…複合材結合層、７…連通気孔、８…第４のアルミナ粒子、９…第１０のアルミナ粒子、１０…第１の製造方法で得られるアルミナ焼結体、１１…連通気孔、２０…第２の製造方法で得られるアルミナ焼結体、３０…第３の製造方法で得られるアルミナ焼結体。 DESCRIPTION OF SYMBOLS 1 ... 1st alumina particle, 2 ... 2nd alumina particle, 3 ... Continuous ventilation hole, 4 ... 3rd alumina particle, 5 ... Composite material, 6 ... Composite material coupling layer, 7 ... Continuous ventilation hole, 8 ... 4th 9 ... 10th alumina particles, 10 ... alumina sintered body obtained by the first production method, 11 ... continuous air holes, 20 ... alumina sintered body obtained by the second production method, 30 ... first 3. An alumina sintered body obtained by the production method of 3.

Claims (10)

骨材としてのアルミナ粒子を造孔材の存在下で焼結することによって得られる、複数の連通気孔を有する気体透過性のアルミナ焼結体であって、
前記連通気孔の平均気孔径が、４００〜１１００Åで、気孔率が、４〜１６％であり、
前記連通気孔の気孔分布（気孔径の分布幅）が、３００〜１１００Åであるアルミナ焼結体。 A gas-permeable alumina sintered body having a plurality of continuous ventilation holes, obtained by sintering alumina particles as an aggregate in the presence of a pore-forming material,
The average pore diameter of the communicating pores is in 400～1100A, porosity, Ri 4-16% der,
The pore distribution of the communicating pores (distribution width of pore diameter), 300～1100A der Ru alumina sintered body. 複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、
粒径が０．２〜０．７μｍで球形度が０．７〜１．０の骨材としての第１のアルミナ粒子と、粒径が０．０１〜０．１μｍの造孔材としての第２のアルミナ粒子とを混合し、前記第１のアルミナ粒子の相互間の空隙に前記第２のアルミナ粒子の複数を埋め込むようにして、１２００〜１４００℃の温度で焼結することによって、前記連通気孔の平均気孔径が、４００〜１１００Åで、気孔率が、４〜１６％であるアルミナ焼結体を得るアルミナ焼結体の製造方法。 A method for producing a gas-permeable alumina sintered body having a plurality of continuous air holes,
First alumina particles as an aggregate having a particle size of 0.2 to 0.7 μm and a sphericity of 0.7 to 1.0, and a first alumina particle as a pore former having a particle size of 0.01 to 0.1 μm. The two alumina particles are mixed, and a plurality of the second alumina particles are embedded in the gaps between the first alumina particles, and sintered at a temperature of 1200 to 1400 ° C. A method for producing an alumina sintered body that obtains an alumina sintered body having an average pore diameter of 400 to 1100 mm and a porosity of 4 to 16%. 得られる前記アルミナ焼結体の気孔分布（気孔径の分布幅）が、３００〜１１００Åである請求項２に記載のアルミナ焼結体の製造方法。 The method for producing an alumina sintered body according to claim 2 , wherein a pore distribution (a distribution width of pore diameters) of the obtained alumina sintered body is 300 to 1100 mm. 前記第２のアルミナ粒子を、前記第１のアルミナ粒子に対して０．２〜１．５質量％の割合で混合する請求項３に記載のアルミナ焼結体の製造方法。 The method for producing an alumina sintered body according to claim 3 , wherein the second alumina particles are mixed at a ratio of 0.2 to 1.5 mass% with respect to the first alumina particles. 複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、
粒径が０．２〜０．７μｍで球形度が０．７〜１．０の骨材としての第３のアルミナ粒子を、二酸化ケイ素（ＳｉＯ2）及び酸化マグネシウム（ＭｇＯ）を含む造孔材としての複合材の存在下で、１２００〜１４００℃の温度で焼結することによって、前記第３のアルミナ粒子の相互間を前記複合材の層によって結合させて、前記連通気孔の平均気孔径が、４００〜１１００Åで、気孔率が、４〜１６％であるアルミナ焼結体を得るアルミナ焼結体の製造方法。 A method for producing a gas-permeable alumina sintered body having a plurality of continuous air holes,
A pore former containing silicon dioxide (SiO 2 ) and magnesium oxide (MgO) as third alumina particles as an aggregate having a particle size of 0.2 to 0.7 μm and a sphericity of 0.7 to 1.0. In the presence of the composite material, the third alumina particles are bonded together by the composite material layer by sintering at a temperature of 1200 to 1400 ° C., and the average pore diameter of the continuous air holes is , A method for producing an alumina sintered body that obtains an alumina sintered body having a porosity of 400 to 1100% and a porosity of 4 to 16%. 前記複合材を、前記第３のアルミナ粒子に対して０．０２〜２質量％の割合で混合する請求項５に記載のアルミナ焼結体の製造方法。 The method for producing an alumina sintered body according to claim 5 , wherein the composite material is mixed at a ratio of 0.02 to 2 mass% with respect to the third alumina particles. 得られる前記アルミナ焼結体の気孔分布（気孔径の分布幅）が、３００〜１１００Åである請求項５又は６に記載のアルミナ焼結体の製造方法。 The method for producing an alumina sintered body according to claim 5 or 6 , wherein a pore distribution (a distribution range of pore diameters) of the obtained alumina sintered body is 300 to 1100cm. 複数の連通気孔を有する気体透過性のアルミナ焼結体を製造する方法であって、
粒径が０．３〜１．０μｍで球形度が０．７〜１．０の骨材としての第４のアルミナ粒子と、粒径が０．２〜０．８μｍの造孔材としての第５のアルミナ粒子とを混合し、前記第４のアルミナ粒子間の空隙に前記第５のアルミナ粒子を嵌め込むようにして、前記１２００〜１４００℃の温度で焼結することによって、前記連通気孔の平均気孔径が、４００〜１１００Åで、気孔率が、４〜１６％であるアルミナ焼結体を得るアルミナ焼結体の製造方法。 A method for producing a gas-permeable alumina sintered body having a plurality of continuous air holes,
Fourth alumina particles as an aggregate having a particle size of 0.3 to 1.0 μm and a sphericity of 0.7 to 1.0, and a fourth alumina particle as a pore former having a particle size of 0.2 to 0.8 μm. 5 alumina particles, and sintering at a temperature of 1200 to 1400 ° C. so that the fifth alumina particles are fitted in the gaps between the fourth alumina particles, whereby the average air volume of the continuous air holes is increased. A method for producing an alumina sintered body, which obtains an alumina sintered body having a pore diameter of 400 to 1100 mm and a porosity of 4 to 16%. 得られる前記アルミナ焼結体の気孔分布（気孔径の分布幅）が、３００〜１１００Åである請求項８に記載のアルミナ焼結体の製造方法。 The method for producing an alumina sintered body according to claim 8 , wherein the obtained alumina sintered body has a pore distribution (a pore width distribution range) of 300 to 1100cm. 前記第５のアルミナ粒子を、前記第４のアルミナ粒子に対して５０〜９５質量％の割合で混合する請求項８又は９に記載のアルミナ焼結体の製造方法。 The method for producing an alumina sintered body according to claim 8 or 9 , wherein the fifth alumina particles are mixed at a ratio of 50 to 95 mass% with respect to the fourth alumina particles.
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